Sierra, Southern yellow-legged frogs marked for protection

Two species of yellow-legged frog found in the upper elevations of the Sierra Nevada were chosen for protection late last week by the California Fish and Game Commission.

The commission voted Thursday to list the Sierra Nevada mountain yellow-legged frog as a threatened species and the Southern mountain yellow-legged frog as endangered.

The Sierra frog is found in the Emigrant Wilderness Area in Tuolumne County and in some areas above 9,000 feet in the Calaveras Ranger District of the Stanislaus National Forest, according to Lindsey Myers, a biologist for the Twain Harte-based Central Sierra Environmental Resource Center. Researchers for the Center for Biological Diversity, which pressed for the listings, place the Southern frog farther south in the Sierra Nevada range as well as other smaller Southern California mountain ranges.

The frogs’ biggest threat has been predation by non-native trout species introduced to alpine lakes, Myers said.
“They just eat all the frogs and the tadpoles as well,” Myers said.

Efforts to reverse those impacts have been ongoing for 12 years, said Mitch Lockhart, an environmental scientist with the fisheries branch of the Department of Fish and Game.

Lockhart said the department has kept up ongoing augmentations to its aerial stocking program and “stayed ahead of the game” in trying to help the frogs recover. Center for Biological Diversity figures show 113 high-elevation lakes in California have been dropped from the stocking program to protect frogs, that Fish and Game has 63 ongoing non-native fish removal projects and that it also is moving frogs from one location to another to repopulate former habitats.

An additional strain on the frogs cited by Myers and the research presented by the Center for Biological Diversity is the impact of cattle grazing in the high country. However, Lockhart said grazing “has been shown to be pretty much negligible” in its effect on yellow-legged frogs.

Ranchers with high-country allotments on Forest Service lands are paying attention to see what protective measures will be enacted in response to the frogs’ listing.

Eloise Fischer Spence, of Altaville, said she is concerned about additional restrictions, having already undertaken management practices prescribed by the Forest Service for yellow-legged frogs as a “sensitive species.”

Fischer Spence said she does not think any of the frogs have been found on her allotments, which mostly run between 6,500 and 8,500 feet, but that some of her allotments do reach above the 9,000-foot mark.

“It’s just another thing that is making it more difficult to stay in business,” Fischer Spence said.

Saving the yellow-legged frog from the threat of extinction will not be easy, Myers said.
It is highly susceptible to a chytrid fungus that attaches to the gills of tadpoles and can also harm adult frogs, she said.

Something as simple as a hiker stepping in a puddle containing the fungus and then stepping in another puddle that contains tadpoles or frogs can be deadly to the amphibians, Myers said.

Nevertheless, she said the species’ listing is encouraging.

“Hopefully, we can bring them back,” Myers said. “They’re really close to the end.”